Horsepower! – 550HP, 505CI Dodge

June 2014

We meet the most interesting people and see the most interesting things when we are on the road, and Mike Hull’s Viper-powered Challenger is just one example. Full of ingenuity, troubleshooting, and good old-fashioned cubic inches, it connected with us in all the right places. Mike says it drives like a sports car, yet is comfortable enough to pilot on a cross-country voyage. He’s also surprised a few exotics in and around his hometown of Salinas, California, and embarrassing a supercar with a piece of vintage Detroit iron is always a good thing.

Transmission

The donor car’s T56 is still in place behind the engine, and it sends power to an 83⁄4 rear with 3.55:1 gears on a Sure Grip differential. Six gears in the transmission and a relatively tall axle ratio means Mike has only used Sixth gear once, and he didn’t wish to divulge how fast the car was moving at the time.

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Fuel

Mike is using a stock, unbaffled Challenger gas tank. We asked if he’d experienced any fuel-starvation issues due to slosh in the tank, to which he replied that the stock pickup was close enough to the bottom of the tank that he’d never had a problem. A Mallory pump supplies the fuel, and Mike reports to getting an average of 15 mpg in mixed driving.

Exhaust

Those are stock Viper tubular exhaust manifolds, and they fit neatly within Magnum Force’s K-member. To them, Mike attached a 3-inch exhaust system with Flowmaster Super 40 mufflers, which he says quell some of the V10’s offbeat Volkswagen-on-steroids exhaust note.

K-Member

Swapping a V10 into a Challenger isn’t too big of a deal, thanks to the parts available from Magnum Force Race Car Fabrication in Campbell, California. The company makes tubular K-members, A-arms, and coilover shock conversions, as well as rear suspension parts, for all Mopars, not just Viper engine swaps. Mike says he worked closely with Magnum Force engineer Jeff Herzog to determine the best placement of the engine. “Jeff experimented with a Viper engine in a Challenger in the stock location [where the V8 would have been], but that was too much weight on the front suspension. So he moved the engine back 2 inches and drove it again. It handled better, but still not as well as he liked, so he kept moving the engine back. At 6 inches rearward, the car felt good to him,” Mike says. If 6 inches was good, Mike felt maybe 8 inches would be better, so he placed his engine 8 inches rearward from the stock location and says, “The car is amazing! It is a blast to drive!” It’s obvious he hit on the right combination of weight distribution and suspension components. Doug Hampton of Salinas, California, sectioned the firewall to clear the engine’s massive setback.

Engine

An ’04 Dodge Viper gave up its life so Mike could make use of its powertrain. He purchased the engine, T56 transmission, and ECM and wiring from X2 Collision, a wrecking yard in Illinois that specializes in Vipers and Ford GTs. This particular donor vehicle recorded a scant 1,400 miles before its undertalented owner rendered it a total loss. Mike received the drivetrain and wiring on a pallet and began plotting the engine swap in 2012.

Other Swap Parts

AFCO coilover shocks replace the stock torsion bars. Mike also purchased an AFCO radiator and oil cooler in the configuration that best fit the plumbing needs dictated by the engine. The Wilwood master cylinder is bolted to a dual-diaphragm booster from a newer Chrysler, but Mike couldn’t remember the exact application. The stock Viper clutch master cylinder was bolted to the firewall below the brake master—the exact position was determined by lining up the pushrod with the clutch pedal. Mike reinforced the firewall in that area to prevent flexing.

The Car

Mike purchased this ’70 Challenger less than three years ago, and looking at the before pictures he sent us, it’s impressive he got it on the road in such a short amount of time. The color is Midnight Stars, a Du Pont Hot Hues color, and other custom touches include ’08 Challenger taillights and front seats, and a center console out of a Ford Fusion.

ECM and Wiring

The computer and harness Mike received from the donor car were not very helpful in terms of unneeded connections and overall complexity. The best alternative came from the Mopar Performance catalog: and ECM and wiring harness for Viper engines in non-Viper vehicles. Part P5155254AB is the ECM, which is tuneable via Diablosport software, and P5007142 is the engine harness. We suspect that Dodge’s participation in NHRA Stock and Super Stock racing with the Drag Pak Challenger program is to thank for the availability of these parts, and you can get them at your local dealership or from Mopar.com.